O’Donovan was sent off for a 13th-minute clash with Sydney’s Jordy Buijs in Newcastle’s 2-1 win on Saturday night at McDonald Jones Stadium. The Irishman was given a straight red and the two-game sanction despite outcries over Buijs’ over-reaction to the seemingly accidental blow to the head.

The Jets had until midday on Tuesday to appeal, but after a delay following an inquiry to the FFA from the club, Newcastle decided against challenging the penalty.

Earlier, Jets coach Ernie Merrick said he was “enormously disappointed” with the sanction before adding “but I don’t really want to say too much”. Merrick was fined $3000 for his post-match comments on the refereeing performance following the 2-2 draw with Western Sydney Wanderers in round 20.

Prompted about the consistency of the judiciary system in relation to O’Donovan’s penalty, Merrick said: “There was one player for example this year, he headbutted someone and got one week, so can you explain that to me? Because I can’t.”

The reference appeared to be about then-Melbourne Victory midfielder Mark Milligan’s contact with Jets defender Daniel Georgievski last November. Milligan was sent off and given just a one-game ban after a change of “serious unsporting conduct”.

O’Donovan was given the charge of “assault on a player (e.g. violent conduct when not challenging for the ball) including an attempted assault on a player” and hit with the minimum sanction for the offence.

“He was off after 10 minutes so that’s virtually a suspension for one game, and now he’s got another two,” Merrick added about the O’Donovan sanction. “And comments made after the game by some players in the opposition side aren’t sanctioned? I just can’t work it out anymore, but I won’t say too much.”

Merrick appeared to refer to comments from Sydney FC skipper Alex Brosque made after the loss to Newcastle, which included: ​"There were a lot of contentious calls, there will be a different referee in the grand final so what happened tonight won’t happen again.”

Merrick said replacing O’Donovan and Japan-bound Andrew Nabbout, the Jets’ main striking options this year, will be a challenge.

“Joey Champness is playing really well every time he comes on and he’s probably due a start,” he said. “There’s Kosta Petratos, as well as maybe moving a midfielder forward, a very attacking type of midfielder, or we can go with one of the younger ones, I guess Angus Thurgate, so we’ve got a few options.”

A plus for the Jets is the expected return of South Americans Ronny Vargas and Pato Rodriguez for their next clash, against Wellington on March 17. Vargas has not played since a sickening ankle injury in round three and Rodriguez (calf) has missed the past two games.

Merrick said Rodriguez was “very fit” and would able to start against Wellington, but Vargas come off the bench as he rebuilds hit match fitness.